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CalDAV Scheduling Extensions to WebDAVApple Inc.1 Infinite LoopCupertinoCA95014USAcyrus@daboo.namehttp://www.apple.com/Oracle Corporation600 Blvd. de Maisonneuve WestSuite 1900MontrealQCH3A 3J2CANADAbernard.desruisseaux@oracle.comhttp://www.oracle.com/Applications
calsifycalschedcalschcaldavcalendarcalendaringschedulingwebcalwebdavicalicalendaritipimiptext/calendarhttp
This document defines extensions to the CalDAV "calendar-access"
feature to specify a standard way of performing scheduling
transactions with iCalendar-based calendar components. This
document defines the "calendar-auto-schedule" feature of
CalDAV.
This document specifies extensions to the
CalDAV "calendar-access"
feature to enable scheduling of
iCalendar-based
calendar components between Calendar Users. This extension
leverages the scheduling methods defined in the iCalendar
Transport-independent Interoperability Protocol (iTIP) to permit Calendar
Users to perform scheduling transactions such as schedule,
reschedule, respond to scheduling request or cancel scheduled
calendar components, as well as search for busy time information.
Discussion of this Internet-Draft is taking place on the mailing
list <https://www.ietf.org/mailman/listinfo/caldav>.
This specification uses much of the same terminology as
iCalendar,
iTIP,
WebDAV, and
CalDAV.
The following definitions are provided to aid the reader
in understanding this specification.
An entity (often a human) that accesses calendar information
.
Software with which the calendar user communicates with a
calendar service or local calendar store to access calendar
information .
A resource that acts as a container of references to
child calendar object resources .
A resource representing a calendar object
(event, to-do, journal entry, or other calendar components)
.
A calendar object resource contained in a calendar
collection for which the server will take care of sending
scheduling messages on behalf of the owner of the calendar
collection.
A scheduling object resource owned by an Organizer.
A scheduling object resource owned by an Attendee.
Add, change or remove operations on a scheduling object
resource for which the server will deliver scheduling
messages to other Calendar Users.
A calendar object resource that describes a scheduling
transaction such as schedule, reschedule, reply, or
cancel.
A resource at which busy time information requests are
targeted.
A collection in which incoming scheduling messages are
delivered.
iTIP outlines
a model where Calendar Users exchange scheduling messages
with one another. Often times, Calendar User Agents are made
responsible for generating and sending scheduling messages as
well as processing incoming scheduling messages. This approach
yields a number of problems, including:
For most updates to a scheduled calendar component, Calendar
User Agents need to address a separate scheduling messages
to the Organizer or the Attendees.
The handling of incoming scheduling messages and the updates
to calendars impacted by those messages only occurs when
Calendar User Agents are active.
Due to the update latency, it is possible for calendars of
different Calendar Users to reflect different, inaccurate
states.
This specification uses an alternative approach where the
server is made responsible for sending scheduling messages
and processing incoming scheduling messages. This approach
frees the Calendar User Agents from the submission and processing
of scheduling messages and ensures better consistency of
calendar data across users' calendars. The operation of
creating, modifying or deleting a scheduled calendar component in
a calendar is enough to trigger the server to deliver the necessary
scheduling messages to the appropriate Calendar Users.
While the scheduling features described in this specification are
based on iTIP,
some of its more complex features have deliberately been left
out in order to keep this specification simple. In particular,
the following iTIP
features are not covered: publishing, countering, delegating,
refreshing and forwarding calendar components, as well as replacing
the Organizer of a calendar component.
The goal of this specification is to provide the essential
scheduling features needed. It is expected that future
extensions will be developed to address the more complex
features.
The Augmented BNF (ABNF) syntax used by this document to specify
the format definition of new iCalendar elements is defined in
.
The Augmented BNF (ABNF) syntax used by this document to specify
the format definition of new message header fields to be used
with the HTTP/1.1 protocol is described in Section 2.1 of
. Since this Augmented BNF uses the
basic production rules provided in Section 2.2 of
, these rules apply to this document
as well.
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL"
in this document are to be interpreted as described in .
The term "protected" is used in the Conformance field of property
definitions as defined in Section 15 of .
This document uses XML DTD fragments (, Section 3.2) as a purely notational convention. WebDAV request and response bodies cannot be validated by a DTD due to the specific extensibility rules defined in Section 17 of [RFC4918] and due to the fact that all XML elements defined by this specification use the XML namespace name "DAV:". In particular:
element names use the "DAV:" namespace,element ordering is irrelevant unless explicitly stated,extension elements (elements not already defined as valid child elements) may be added anywhere, except when explicitly stated otherwise,extension attributes (attributes not already defined as valid for this element) may be added anywhere, except when explicitly stated otherwise.
The XML elements specified in this document are defined in the
"urn:ietf:params:xml:ns:caldav" XML namespace registered by
CalDAV.
When XML element types in the namespaces "DAV:" and "urn:ietf:params:xml:ns:caldav" are referenced in this document outside of the context of an XML fragment, the strings "DAV:" and "CALDAV:" will be prefixed to the element types, respectively.
This document inherits, and sometimes extends, DTD productions from Section 14 of .
Also note that some CalDAV XML element names are identical to WebDAV XML element names, though their namespace differs. Care must be taken not to confuse the two sets of names.
The process of scheduling an event between different parties
often involves a series of steps with different actors playing
particular roles during the whole process. Typically there is
an event "Organizer" whose role is to setup an event between
one or more "Attendees", and this is done by sending out
invitations and handling responses from each Attendee.
This process can typically be broken down into two phases.
In the first phase, the Organizer will query the busy time
information of each Attendee to determine the most appropriate
time for the event. This request is sometimes called a freebusy
lookup.
In the second phase, the Organizer sends out invitations to each
Attendee using the time previously determined from the freebusy lookup. There then follows
exchanges between Organizer and Attendees regarding the invitation.
Some Attendees may choose to attend at the time proposed by the
Organizer, others may decline to attend. The Organizer needs to
process each of the replies from the Attendees and take appropriate
action to confirm the event, reschedule it or perhaps cancel it.
The user expectation as to how a calendaring and scheduling system
should respond in each of these two phases is somewhat different. In
the case of a freebusy lookup, users expect to get back results
immediately so that they can then move on to the invitation phase
as quickly as possible. In the case of invitations, it is expected
that each Attendee will reply with their participation status in
their own time, so delays in receiving replies are anticipated. Thus
calendaring and scheduling systems should treat these two operational
phases in different ways to accommodate the user expectations,
and this specification does that.
While the scenario described above only covers the case of scheduling
events between Calendar Users, and requesting busy time information,
this specification also provides support for the scheduling of
to-dos between Calendar Users. For the majority of the following
discussion, scheduling of events and freebusy lookups will be
discussed, as these are the more common operations.
A server that supports the features described in this document MUST
include "calendar-auto-schedule" as a field in the DAV response
header from an OPTIONS request on any resource that supports any
scheduling actions, properties, privileges or methods.
To advertise support for the CalDAV "calendar-auto-schedule" feature
a server is REQUIRED to support and advertise support for the CalDAV "calendar-access" feature.
>> Request <<>> Response <<
In this example, the OPTIONS response indicates that the server
supports the "calendar-access" and "calendar-auto-schedule"
features and that resource "/home/cyrus/calendars/inbox/"
supports the scheduling actions, properties, privileges and
methods defined in this specification.
This specification introduces new collection resource types
that are used to manage scheduling object resources, scheduling
privileges as well as provide scheduling functionality.
A scheduling Outbox collection is used as the target for
busy time information requests.
A scheduling Outbox collection MUST report the DAV:collection
and CALDAV:schedule-outbox XML elements in the value of the
DAV:resourcetype property. The element type declaration for
CALDAV:schedule-outbox is:
]]>
Example:
]]>
New WebDAV ACL privileges can
be set on the scheduling Outbox collection to control who is
allowed to send scheduling messages on behalf of the Calendar
User associated with the scheduling Outbox collection.
See for more details.
A scheduling Outbox collection MUST NOT be a child (at any depth)
of a calendar collection resource.
The following WebDAV properties specified in CalDAV "calendar-access"
MAY also be defined on scheduling Outbox collections:
CALDAV:supported-calendar-component-set - when present this
indicates the allowed calendar component types for scheduling
messages submitted to the scheduling Outbox collection with
the POST method.
CALDAV:supported-calendar-data - when present this indicates
the allowed media types for scheduling messages submitted to
the scheduling Outbox collection with the POST method.
CALDAV:max-resource-size - when present this indicates the
maximum size of a resource in octets that the server is
willing to accept for scheduling messages submitted to the
scheduling Outbox collection with the POST method.
CALDAV:min-date-time - when present this indicates the earliest
date and time (in UTC) that the server is willing to accept for
any DATE or DATE-TIME value in scheduling messages submitted
to the scheduling Outbox collection with the POST method.
CALDAV:max-date-time - when present this indicates the latest
date and time (in UTC) that the server is willing to accept for
any DATE or DATE-TIME value in scheduling messages submitted
to the scheduling Outbox collection with the POST method.
CALDAV:max-instances - when present this indicates the maximum
number of recurrence instances in scheduling messages submitted
to the scheduling Outbox collection with the POST method.
CALDAV:max-attendees-per-instance - when present this indicates
the maximum number of ATTENDEE properties in any instance
of scheduling messages submitted to the scheduling Outbox
collection with the POST method.
The use of child resources in a scheduling Outbox collection is reserved for future revisions or extensions of this specification.
A scheduling Inbox collection contains copies of incoming
scheduling messages. These may be requests sent by an
Organizer, or replies sent by an Attendee in response to
a request.
A scheduling Inbox collection MUST report the DAV:collection
and CALDAV:schedule-inbox XML elements in the value of the
DAV:resourcetype property. The element type declaration for
CALDAV:schedule-inbox is:
]]>
Example:
]]>
Scheduling Inbox collections MUST only contain calendar object
resources that obey the restrictions specified in iTIP. Consequently,
scheduling Inbox collections MUST NOT contain any types of
collection resources. Restrictions defined in Section 4.1 of
CalDAV "calendar-access" on calendar
object resources contained in calendar collections (e.g., "UID"
uniqueness) don't apply to calendar object resources contained in
a scheduling Inbox collection. Thus, multiple calendar object resources
contained in a scheduling Inbox collection can have the same "UID"
property value (i.e., multiple scheduling messages for the same
calendar component).
New WebDAV ACL privileges can
be set on the scheduling Inbox collection to control who the
Calendar User associated with the scheduling Inbox collection
will accept scheduling messages from.
See for more details.
A scheduling Inbox collection MUST NOT be a child (at any depth)
of a calendar collection resource.
The following WebDAV properties specified in
CalDAV "calendar-access" MAY
also be defined on scheduling Inbox collections:
CALDAV:calendar-timezone - when present this contains a
time zone that the server can use when calendar date-time
operations are carried out, for example when a time-range
CALDAV:calendar-query REPORT is targeted at a scheduling
Inbox collection.
CALDAV:supported-calendar-component-set - when present this
indicates the allowed calendar component types for scheduling
messages delivered to the scheduling Inbox collection.
CALDAV:supported-calendar-data - when present this indicates
the allowed media types for scheduling messages delivered
to the scheduling Inbox collection.
CALDAV:max-resource-size - when present this indicates
the maximum size of a resource in octets that the server
is willing to accept for scheduling messages delivered to
the scheduling Inbox collection.
CALDAV:min-date-time - when present this indicates the
earliest date and time (in UTC) that the server is willing
to accept for any DATE or DATE-TIME value in scheduling
messages delivered to the scheduling Inbox collection.
CALDAV:max-date-time - when present this indicates the
latest date and time (in UTC) that the server is willing
to accept for any DATE or DATE-TIME value in scheduling
messages delivered to the scheduling Inbox collection.
CALDAV:max-instances - when present this indicates the
maximum number of recurrence instances in scheduling messages
delivered to the scheduling Inbox collection.
CALDAV:max-attendees-per-instance - when present this
indicates the maximum number of ATTENDEE properties in any
instance of scheduling messages delivered to the scheduling
Inbox collection.
This specification extends the CALDAV:calendar-query and
CALDAV:calendar-multiget REPORTs to return results for calendar
object resources in scheduling Inbox collections when the report
directly targets such a collection. That is, the Request-URI for a
report MUST be the URI of the scheduling Inbox collection or of
a child resource within a scheduling Inbox collection. A report
run on a regular collection that includes a scheduling Inbox
collection as a child resource at any depth MUST NOT examine or
return any calendar object resources from within any scheduling
Inbox collections.
When a CALDAV:calendar-query REPORT includes a time-range query
and targets a scheduling Inbox collection, if any calendar
object resources contain "VEVENT" calendar components that do
not include a "DTSTART" iCalendar property (as allowed by iTIP) then such components
MUST always match the time-range query test.
Note that the CALDAV:free-busy-query REPORT is not supported on
scheduling Inbox collections.
When a calendar object resource is created, modified or removed
from a calendar collection (either via a PUT, DELETE, COPY or
MOVE HTTP request), the server examines the calendar data and
checks to see whether the data represents a scheduling object
resource. If it does, the server will automatically attempt to
deliver a scheduling message to the appropriate Calendar Users.
Several types of scheduling operation can occur in this case,
equivalent to iTIP "REQUEST", "REPLY", "CANCEL", and "ADD"
operations.
Calendar object resources on which the server performs automatic
scheduling transactions are referred to as scheduling object
resources. There are two types of scheduling object resources:
organizer scheduling object resources, and attendee scheduling
object resources.
A calendar object resource is considered to be a valid
organizer scheduling object resource if the "ORGANIZER"
iCalendar property is present and set in all the calendar
components to a value that matches one of the calendar user
addresses of the owner of the calendar collection.
A calendar object resource is considered to be a valid attendee
scheduling object resource if the "ORGANIZER" iCalendar
property is present and set in all the calendar components
to the same value and doesn't match one of the calendar user
addresses of the owner of the calendar collection, and that
at least one of the "ATTENDEE" iCalendar property values
match one of the calendar user addresses of the owner of the
calendar collection.
The creation of attendee scheduling object resources is
typically done by the server, with the resource being
stored in an appropriate calendar collection.
The server's behavior when processing a scheduling object
resource depends on whether it is owned by the Organizer or
an Attendee specified in the calendar data.
An Organizer can create, modify or remove a scheduling object
resource by issuing HTTP requests with an appropriate
method. The create, modify and remove behaviors for
the server are each described next, and the way these
are invoked via HTTP requests is described in
.
When a scheduling object resource is created by the
Organizer, the server will inspect each "ATTENDEE"
property to determine if a scheduling message
should be delivered to this Attendee according to
the value of the "SCHEDULE-AGENT" property parameter (see )
as described in the table below:
The attempt to deliver the scheduling message will either
succeed or fail. In all cases, the server MUST add a
"SCHEDULE-STATUS" iCalendar property parameter (see ) to the
"ATTENDEE" iCalendar property in the scheduling object
resource being created, and set its value as described in
. This will result
in the created calendar object resource differing from
the calendar data sent in the HTTP request. As a result
clients can reload the calendar data from the server
as soon as it is created on the server in order to
update to the new server generated state information.
Servers MUST NOT set the "SCHEDULE-STATUS" property
parameter on the "ATTENDEE" property of Attendees
for which it did not attempt to deliver a scheduling
message.
Restrictions:
The server MAY reject any attempt to set the
"PARTSTAT" iCalendar property parameter value of
the "ATTENDEE" iCalendar property of other users in
the calendar object resource to a value other than
"NEEDS-ACTION" if the "SCHEDULE-AGENT" property
parameter value is not present or set to the value
"SERVER". To maintain consistency across Organizers
and Attendees, a server will typically choose to
enforce the requirement that only an Attendee can
change their own "PARTSTAT" to a value other than
"NEEDS-ACTION".
The server MAY reject attempts to create a scheduling
object resource that specifies a "UID" property value
already specified in a scheduling object resource
contained in another calendar collection of the
Organizer.
The server MUST take into account scheduling privileges
as described in when handling
the creation of a scheduling object resource.
Restrictions on calendar object resources defined
in Section 4.1 of MUST
also be enforced.
When a scheduling object resource is modified by the
Organizer, the server will inspect each "ATTENDEE" property
in the new calendar data to determine which ones have the
"SCHEDULE-AGENT" iCalendar property parameter. It will then
need to compare this with the "ATTENDEE" properties in the
existing calendar object resource that is being modified.
For each Attendee in the old and new calendar data on a
per-instance basis, and taking into account the addition or
removal of Attendees, the server will determine whether to
deliver a scheduling message to the Attendee. The following
table determines whether the server needs to deliver a
scheduling message, and if so which iTIP scheduling method
to use. The values "SERVER", "CLIENT", and "NONE" in the top
and left titles of the table refer to the "SCHEDULE-AGENT"
parameter value of the "ATTENDEE" property, and the values
"<Absent>" and "<Removed>" are used to cover
the cases where the "ATTENDEE" property is not present
(Old) or is being removed (New).
| SERVER | CLIENT | NONE |
| | | (default) | | |
+===+===========+===========+===========+===========+===========+
| | | -- | REQUEST / | -- | -- |
| | | | ADD | | |
| +-----------+-----------+-----------+-----------+-----------+
| | SERVER | CANCEL | REQUEST | CANCEL | CANCEL |
| O | (default) | | | | |
| l +-----------+-----------+-----------+-----------+-----------+
| d | CLIENT | -- | REQUEST / | -- | -- |
| | | | ADD | | |
| +-----------+-----------+-----------+-----------+-----------+
| | NONE | -- | REQUEST / | -- | -- |
| | | | ADD | | |
+---+-----------+-----------+-----------+-----------+-----------+
]]>The attempt to deliver the scheduling message will either succeed or fail. In all cases, the server MUST add a "SCHEDULE-STATUS" iCalendar property parameter to the "ATTENDEE" iCalendar property in the scheduling object resource being modified, and set its value as described in . This will result in the created calendar object resource differing from the calendar data sent in the HTTP request. As a result clients MAY reload the calendar data from the server as soon as it is modified on the server in order to update to the new server generated state information.Restrictions:
The server MAY reject any attempt to set the "PARTSTAT" iCalendar property parameter value of the "ATTENDEE" iCalendar property of other users in the calendar object resource to a value other than "NEEDS-ACTION" if the "SCHEDULE-AGENT" property parameter value is not present or set to the value "SERVER". To maintain consistency for Organizers and Attendees, a server will typically choose to enforce the requirement that only an Attendee can change their own "PARTSTAT" to a value other than "NEEDS-ACTION".
The server MUST take into account scheduling privileges
as described in when handling
the modification of a scheduling object resource.
Restrictions on calendar object resources defined in Section 4.1 of MUST also be enforced.When a scheduling object resource is removed by the Organizer, the server will inspect each "ATTENDEE" property in the scheduling object resource being removed to determine which ones have the "SCHEDULE-AGENT" iCalendar property parameter.For each Attendee the server will determine whether to attempt to deliver a scheduling message into the Attendee's scheduling Inbox collection, based on the table below:Restrictions:
The server MUST take into account scheduling privileges
as described in when handling
the deletion of a scheduling object resource.
An Attendee can create, modify or remove a scheduling object resource by issuing HTTP requests with an appropriate method. The create, modify and remove behaviors for the server are each described next, and the way these are invoked via HTTP requests is described in .
Attendees are allowed to make some changes to a scheduling
object resource, though key properties such as start time,
end time, location, and summary are typically under the
control of the Organizer.
The server MUST allow Attendees to:
change their own "PARTSTAT" iCalendar property parameter value.add, modify or remove any "TRANSP" iCalendar properties.add, modify or remove any "PERCENT-COMPLETE" iCalendar properties.add, modify or remove any "VALARM" iCalendar components.add, modify or remove the "CALSCALE" iCalendar property within the top-level "VCALENDAR" component.modify the "PRODID" iCalendar property within the top-level "VCALENDAR" component.add "EXDATE" iCalendar properties and possibly remove components for overridden recurrence instances.add, modify or remove any "CREATED", "DTSTAMP" and "LAST-MODIFIED" iCalendar properties.add new components to represent overridden recurrence instances, provided the only changes to the recurrence instance follow the rules above.Typically an Attendee does not create scheduling object resources, as scheduling messages delivered to them on the server are automatically processed by the server and placed on one of their calendars (see ). However, in some cases a scheduling message may get delivered directly to the client, and the Attendee may wish to store that on the server. In that case the client creates a scheduling object resource in a suitable calendar belonging to the Attendee. Once stored, it is then subject to the usual rules for attendee scheduling object resources.In some cases a server may not be able to process an Attendee scheduling object resource that originated from another system (i.e., where the server is unable to deliver scheduling messages to the Organizer). In such cases the server MUST add a "SCHEDULE-AGENT" iCalendar property parameter to all "ORGANIZER" iCalendar properties in the resource and set the value of each to "NONE". The server MAY reject any attempt by the client to remove the "SCHEDULE-AGENT" property parameter or change its value.When a scheduling object resource is modified by an Attendee, the server will inspect the changes by comparing it with the existing scheduling object resource being replaced.If the Attendee changes one or more "PARTSTAT" iCalendar property values on any component, or adds an overridden component with a changed "PARTSTAT" property, then the server MUST deliver an iTIP "REPLY" scheduling message to the Organizer to indicate the new participation status of the Attendee.The attempt to deliver the scheduling message will either succeed or fail. In all cases, the server MUST add a "SCHEDULE-STATUS" iCalendar property parameter to the "ORGANIZER" iCalendar property in the scheduling object resource being created, and set its value as described in . This will result in the created calendar object resource differing from the calendar data sent in the HTTP request. As a result clients MAY reload the calendar data from the server as soon as it is stored in order to update to the new server generated state information.When a scheduling object resource is removed by the Attendee, one of two possibilities exist:
If the HTTP request contains a "Schedule-Reply" request header set to the value "T" or there is no "Schedule-Reply" request header, then the server MUST attempt to deliver a scheduling message to the Organizer indicating that the Attendee has a "PARTSTAT" iCalendar property parameter value set to "DECLINED". That is, the Attendee has chosen not to attend any instances. If the server is unable to deliver the scheduling message, the remove action MUST fail, and an appropriate "SCHEDULE-STATUS" iCalendar property parameter set on the "ORGANIZER" property in the scheduling object resource stored by the server.If the HTTP request contains a request header "Schedule-Reply" set to the value "F", the server MUST NOT attempt to deliver a scheduling message. The resource is simply removed. This provides the client a way to silently remove unwanted scheduling attempts.This section describes how use of various HTTP methods on a scheduling object resource will cause a create, modify or remove action on that resource as described above. The use of these methods is subject to the restrictions in , in addition to what is described below.When a PUT method request is received, the server will execute the following actions, provided all appropriate preconditions are met:Existing Destination ResourceResulting Destination ResourceServer ActionNoneCalendar object resourceNoneNoneScheduling object resourceCreateCalendar object resourceCalendar object resourceNoneCalendar object resourceScheduling object resourceCreateScheduling object resourceCalendar object resourceRemoveScheduling object resourceScheduling object resourceModifyWhen a COPY method request is received, the server will execute the following actions based on the source and destination collections in the request:Source CollectionDestination CollectionServer ActionNon-calendar collectionNon-calendar collectionNoneNon-calendar collectionCalendar collection(1)Calendar collectionNon-calendar collectionNoneCalendar collectionCalendar collectionNoneNote 1. The same rules as used for PUT above are applied for the destination of the COPY request.
When a MOVE method request is received, the server will
execute the following actions based on the source and
destination collections in the request:
Source CollectionDestination CollectionServer ActionNon-calendar collectionNon-calendar collectionNoneNon-calendar collectionCalendar collection(1)Calendar collectionNon-calendar collection(2)Calendar collectionCalendar collectionNoneNote 1. The same rules as used for PUT above are applied for the destination of the MOVE request.Note 2. The same rules as used for DELETE below are applied for the source of the MOVE request.
When a DELETE method is targeted at a scheduling object
resource the server will execute the Remove action.
When a DELETE method is targeted at a calendar collection
the server will execute the Remove action on all scheduling
object resources contained in the calendar collection.
This specification defines additional method preconditions
(see Section 16 of WebDAV)
to provide machine-parsable information in error responses.
unique-scheduling-object-resourceurn:ietf:params:xml:ns:caldavPUT, COPY, and MOVE409 Conflict
(precondition) --
Servers MAY reject requests to create a scheduling
object resource with an iCalendar "UID" property value
already in use by another scheduling object resource
owned by the same user in other calendar collections.
Servers SHOULD report the URL of the scheduling object
resource that is already making use of the same "UID"
property value in the DAV:href element.
]]>/home/bernard/calendars/personal/abc123.ics
]]>same-organizer-in-all-componentsurn:ietf:params:xml:ns:caldavPUT, COPY, and MOVE409 Conflict
(precondition) -- All the calendar components in a
scheduling object resource MUST contain the same "ORGANIZER"
property value when present.
]]>
]]>allowed-organizer-scheduling-object-changeurn:ietf:params:xml:ns:caldavPUT, COPY, and MOVE409 Conflict
(precondition) --
Servers MAY impose restrictions on modifications allowed by an
Organizer. For instance, servers MAY prevent the Organizer
setting the "PARTSTAT" property parameter to a value other than
"NEEDS-ACTION" if the corresponding "ATTENDEE" property has
the "SCHEDULE-AGENT" property parameter set to "SERVER",
or has no "SCHEDULE-AGENT" property parameter. See .
]]>
]]>allowed-attendee-scheduling-object-changeurn:ietf:params:xml:ns:caldavPUT, COPY, and MOVE409 Conflict
(precondition) --
Servers MAY impose restrictions on modifications allowed
by an Attendee. Attendee modifications that servers MUST allow
are specified in .
]]>
]]>
Whenever the server generates a scheduling message for
delivery to a Calendar User, it MUST ensure that a
"DTSTAMP" iCalendar property is present and MUST set
the value to the UTC time that the scheduling message
was generated (as required by iCalendar).
iTIP places
certain requirements on how the "SEQUENCE" iCalendar property
value in scheduling messages changes. The server MUST ensure
that for each type of scheduling operation, the "SEQUENCE"
iCalendar property value is appropriately updated. If the
client does not update the "SEQUENCE" iCalendar property itself
when that is required, the server MUST update the property.
When delivering scheduling messages for recurring calendar
components to Attendees, servers MUST ensure that Attendees
only get information about recurrence instances that
explicitly include them as an Attendee.
For example, if an Attendee is invited to a single recurrence
instance of a recurring event, and no others, the scheduling
object resource contained in the Organizer's calendar
collection will contain an overridden instance in the form
of a separate calendar component. That separate calendar
component will include the "ATTENDEE" property referencing
the "one-off" Attendee. That Attendee will not be listed
in any other calendar components in the scheduling object
resource. The scheduling message that will be delivered
to the Attendee will only contain information about this
overridden instance.
As another example, an Attendee could be excluded from one
instance of a recurring event. In that case the scheduling
object resource contained in the calendar collection of
the Organizer will include an overridden instance with an
"ATTENDEE" list that does not include the Attendee being
excluded. The scheduling message that will be delivered to
the Attendee will not specify the overridden instance but
rather include an "EXDATE" property in the master recurring
component defining the recurrence set.
The iCalendar property parameter "SCHEDULE-FORCE-SEND" defined
in can be used
by a Calendar User to force the server to send a scheduling
message to an Attendee or the Organizer in a situation where
the server would not normally send a scheduling message.
For instance, an Organizer could use this property parameter
to request an Attendee, that previously declined an invitation,
to reconsider their participation status without being forced to
modify the event.
Scheduling operations can cause the delivery of a scheduling
message into an Organizer's or Attendee's scheduling Inbox
collection. In the former case the scheduling messages are
replies from Attendees, in the latter case the scheduling
messages are requests, cancellations or additions from the
Organizer.
The server will automatically process incoming scheduling
messages and make them available in the scheduling Inbox
collection as an indicator to the client that a scheduling
operation has taken place.
The server MUST take into account privileges
on the scheduling Inbox collection, when processing incoming
scheduling messages, to determine whether delivery of the
scheduling message is allowed. Privileges on
calendars containing any matching scheduling object resource are
not considered in this case. Additionally, servers MUST take
into account any scheduling Inbox collection preconditions
(see ) when delivering the
scheduling message, and it MUST take into account the similar
preconditions on any calendar collection which contains, or
would contain, the corresponding scheduling object resource.
For a scheduling message reply sent by an Attendee, the
server first locates the corresponding scheduling object
resource belonging to the Organizer.
The server MUST then update the "PARTSTAT" iCalendar property parameter
value of each "ATTENDEE" iCalendar property in the scheduling
object resource to match the changes indicated in the reply
(taking into account the fact that an Attendee could have
created a new overridden iCalendar component to indicate
different participation status on one or more recurrence
instances of a recurring event).
The server MUST also update or add the "SCHEDULE-STATUS"
property parameter on each matching "ATTENDEE" iCalendar
property and sets its value to that of the "REQUEST-STATUS"
property in the reply, or to "2.0" if "REQUEST-STATUS" is not
present (also taking into account recurrence instances). If
there are multiple "REQUEST-STATUS" properties in the
reply, the "SCHEDULE-STATUS" property parameter value is
set to a comma-separated list of status codes, one from each
"REQUEST-STATUS" property.
The server SHOULD send scheduling messages to all the other
Attendees indicating the change in participation status of
the Attendee replying, subject to the recurrence requirements
of .
In this case, the scheduling message MUST only appear in the
Organizer's scheduling Inbox collection once all automatic
processing has been done.
For a scheduling message sent by an Organizer, the server first
tries to locate a corresponding scheduling object resource
belonging to the Attendee. If no matching scheduling object
resource exists, the server treats the scheduling message as
a new message, otherwise it is treated as an update.
In the case of a new message, the server MUST process the
scheduling message and create a new scheduling object resource
in an appropriate calendar collection for the Attendee.
In the case of an update, the server MUST process the
scheduling message and update the matching scheduling
object resource belonging to the Attendee to reflect
the changes sent by the Organizer.
In any case, the scheduling message MUST only appear
in the Attendee's scheduling Inbox collection once all
automatic processing has been done.
The server is REQUIRED to process scheduling messages that specify a request for a new calendar component received for an Attendee
by creating a new scheduling object
resource in a calendar collection belonging to the Attendee. A Calendar User
who can participate as an Attendee in a scheduling operation
MUST have at least one valid calendar collection available. If there is no valid
calendar collection, then the server MUST reject the attempt to
deliver the scheduling message to the Attendee.
Servers MAY provide support for a default calendar collection, that is,
the calendar collection in which new scheduling object resources will be
created on reception of scheduling messages that specify a request for
a new calendar component. The CALDAV:schedule-default-calendar-URL
WebDAV property, which MAY be defined on the scheduling Inbox
collection of a Calendar User, specifies if this Calendar User has a
default calendar collection. See
.
Servers MUST create new scheduling object resources in the default calendar collection, if the CALDAV:schedule-default-calendar-URL WebDAV property is set.
Servers MAY allow clients to change the default
calendar collection by changing the value of the
CALDAV:schedule-default-calendar-URL WebDAV property on the
scheduling Inbox collection. However, they MUST ensure that
any new value stored for that property refers to a valid
calendar collection belonging to the owner of the scheduling
inbox collection.
Servers MUST reject any attempt to delete the default calendar
collection.
This specification defines additional method preconditions
(see Section 16 of WebDAV)
to provide machine-parsable information in error responses.
default-calendar-delete-allowedurn:ietf:params:xml:ns:caldavDELETE403 Forbidden
(precondition) --
The client attempted to delete the calendar collection
currently referenced by the
CALDAV:schedule-default-calendar-URL property, or attempted
to remove the CALDAV:schedule-default-calendar-URL property
on the scheduling Inbox collection on a server that doesn't
allow such operations.
]]>
]]>valid-schedule-default-calendar-URLurn:ietf:params:xml:ns:caldavPROPPATCH403 Forbidden
(precondition) --
The client attempted to set the
CALDAV:schedule-default-calendar-URL property to a DAV:href
element that doesn't reference a valid calendar collection.
Note: Servers that don't allow clients to change the
CALDAV:schedule-default-calendar-URL property would simply
return the DAV:cannot-modify-protected-property precondition
defined in Section 16 of WebDAV.
]]>
]]>
Once the processing of an incoming scheduling message is completed
by the server, the message is made available as a child resource
in the scheduling Inbox collection of the Calendar User that
received the message, to serve as a notification that a change has
been made to the corresponding scheduling object resource.
Scheduling messages are typically removed from the scheduling
Inbox collection by the client once it has acknowledged the change.
The POST method is used to request busy time information
of one or more Calendar Users by targeting the request at
a scheduling Outbox collection. The request body of a POST
method MUST contain a "VFREEBUSY" calendar component with
the "METHOD" iCalendar property set to the value "REQUEST" as specified in Section 3.3.2 of
iTIP.
The resource identified by the Request-URI
MUST be a resource collection of type
CALDAV:schedule-outbox.
The following are examples of response codes one would
expect to be used for this method. Note, however, that unless
explicitly prohibited any 2/3/4/5xx series response code may
be used in a response.
200 (OK) -
The command succeeded.
204 (No Content) -
The command succeeded.
400 (Bad Request) -
The client has provided an invalid scheduling message.
403 (Forbidden) -
The client cannot submit a scheduling message to the
specified Request-URI.
404 (Not Found) -
The URL in the Request-URI was not present.
423 (Locked) - The specified resource is locked and
the client either is not a lock owner or the lock type
requires a lock token to be submitted and the client did
not submit it.
This specification defines additional method preconditions
for the POST method. Preconditions defined in
WebDAV ACL and
CalDAV that applies to the
POST method are also listed here for completeness.
need-privilegesDAV:POST403 Forbidden
(precondition) --
The currently authenticated user MUST be granted the
CALDAV:schedule-send or CALDAV:schedule-send-freebusy privilege on the scheduling Outbox collection being targeted by
the request.
]]>/home/bernard/calendars/outbox/
]]>supported-collectionurn:ietf:params:xml:ns:caldavPOST400 Bad Request
(precondition) --
The Request-URI MUST identify the location of a
scheduling Outbox collection.
]]>
]]>supported-calendar-dataurn:ietf:params:xml:ns:caldavPOST400 Bad Request
(precondition) --
The resource body submitted in the POST request MUST
be a supported media type (e.g., text/calendar).
]]>
]]>valid-calendar-dataurn:ietf:params:xml:ns:caldavPOST400 Bad Request
(precondition) --
The resource submitted in the POST request MUST be valid
data for the media type being specified (e.g., a valid
iCalendar object).
]]>
]]>valid-scheduling-messageurn:ietf:params:xml:ns:caldavPOST400 Bad Request
(precondition) --
The resource submitted in the POST request MUST obey all
restrictions specified for the POST request (e.g., the
scheduling message follow the restrictions of iTIP).
]]>
]]>organizer-allowedurn:ietf:params:xml:ns:caldavPOST409 Conflict
(precondition) --
The Calendar User identified by the "ORGANIZER" property
in the POST request's scheduling message MUST be the
Calendar User (or one of the Calendar Users) associated
with the scheduling Outbox collection being targeted by
the request;
]]>
]]>max-resource-sizeurn:ietf:params:xml:ns:caldavPOST403 Forbidden
(precondition) --
The resource submitted in the POST request MUST have
a size in octets less than or equal to the value of the
CALDAV:max-resource-size property
(defined in Section 5.2.5 of )
specified on the scheduling Outbox collection targeted
by the request.
]]>
]]>
A POST request may deliver a scheduling message to one or more
Calendar Users. Since the behavior of each recipient
may vary, it is useful to get response status information for
each recipient in the overall POST response. This specification
defines a new XML response to convey multiple recipient status.
A response to a POST method that indicates status for one
or more recipients MUST be a CALDAV:schedule-response XML
element. This MUST contain one or more CALDAV:response
elements for each recipient, with each of those containing
elements that indicate which recipient they correspond to,
the scheduling status for that recipient,
any error codes and an optional description.
See .
In the case of a freebusy request, the CALDAV:response elements
can also contain CALDAV:calendar-data elements which contain
freebusy information (e.g., an iCalendar VFREEBUSY component)
indicating the busy state of the corresponding recipient,
assuming that the freebusy request for that recipient
succeeded. See for an example freebusy request and response.
Because replies from Attendees and updates from Organizers
are automatically processed by the server, clients might
be in a situation where their copy of a calendar resource
is different from the one currently on the server. When an
Attendee or Organizer makes a change to the client's copy
of the calendar resource, if the client writes the data
to the server it could overwrite the changes already made
there. Typically, clients use the ETag value and If-Match
request headers to avoid the "lost update problem".
Calendar user agents can also use ETag and If-Match to avoid
this problem. However, when doing so the client will likely
have to resolve the differences between the new resource and
the original one, and the changes made by the Attendee or
Organizer in the client. This can be a complicated comparison
particularly when recurring components are present.
Additionally, the data on the server may change frequently as
Attendees change their participation status, triggering updates
to the Organizer and consequently other Attendees' copies of
the scheduling object resource. If the ETag/If-Match behavior
were used, clients would be forced to reconcile their cached
copy of a scheduling object resource with the updated one on
the server in order to attempt to write the user's changes
back. This could lead to a race condition that can effectively
result in a temporary denial of service when, for example,
there is an event with a large Attendee list. A "storm" of
updates will occur if Attendees all start responding at the
same time, and this would prevent Attendees and the Organizer
from being able to update their own copies of the scheduling
object resource as the server copy is changing frequently.
What would be preferable is having the server determine the
best way to merge changes made on the server with changes being
made by the client. For example, if an Attendee changes their
participation status and triggers an update to the Organizer's
copy of the event, but the Organizer also updates their cached
copy of the event and attempts to write it back, rather than
failing on a conditional If-Match when the Organizer writes
their data, the server would instead take the changes made
by the Organizer and apply the Attendee changes and store
the result. Thus a form of "weak" ETag matching behavior is
needed such that scheduling changes made automatically on
the server do not invalidate the tag, so that when clients
store data conditionally based on the tag value, the server
knows it can apply the merge behavior.
In order to do that, this specification introduces a
new WebDAV resource property CALDAV:schedule-tag with a
corresponding response header "Schedule-Tag", and a new
"If-Schedule-Tag-Match" request header to allow client
changes to be appropriately merged with server changes in
the case where the changes on the server were the result
of an "inconsequential" scheduling message update. An
"inconsequential" scheduling message is one which simply
updates the status information of Attendees due to a reply
from an Attendee.
Servers MUST support requests targeted at scheduling
object resources using the "If-Schedule-Tag-Match" request header.
Consequently, the server MUST support the "Schedule-Tag" response
header and CALDAV:schedule-tag property for scheduling object
resources. Servers MUST automatically resolve conflicts with
"inconsequential" changes done to scheduling object resources when
the "If-Schedule-Tag-Match" request header is specified.
The If-Schedule-Tag-Match request header applies only to the
Request-URI, and not to the Destination of a COPY or MOVE in the
same way as the If-Match request header.
Clients SHOULD use the If-Schedule-Tag-Match header on requests that update scheduling object resources.
A response to any successful GET or PUT request targeting
a scheduling object resource MUST include a Schedule-Tag
response header with the value set to the same value as the
CALDAV:schedule-tag WebDAV property of the resource.
A response to any successful COPY or MOVE request that
specifies a Destination request header targeting a scheduling
object resource MUST include a Schedule-Tag response header
with the value set to the same value as the CALDAV:schedule-tag
WebDAV property of the resource identified in the Request-URI.
The Schedule-Tag feature is designed to be used to address
the problem of "inconsequential" changes on the server
only. Normal ETag operations are used in all other cases,
e.g., for synchronization.
The value of the CALDAV:schedule-tag property changes according
to these rules:
For an Organizer's copy of a scheduling object resource:
The server MUST NOT change the CALDAV:schedule-tag
property value when the scheduling object resource
is updated as the result of automatically processing
a scheduling message reply from an Attendee. For
instance, when an Attendee replies to the Organizer,
the CALDAV:schedule-tag property is unchanged after
the Organizer's scheduling object resource has been
automatically updated by the server with the Attendee's
new participation status.
The server MUST change CALDAV:schedule-tag property
value when the scheduling object resource is changed
directly via an HTTP request (e.g., PUT, COPY or MOVE).
For an Attendee's copy of a scheduling object resource:
The server MUST change the CALDAV:schedule-tag
property value when the scheduling object resource
is changed as the result of processing a
scheduling message update from an Organizer
that contains changes other than just the participation
status of Attendees.
The server MUST NOT change the CALDAV:schedule-tag
property value when the scheduling object resource
is changed as the result of processing a scheduling
message update from an Organizer that only specify
changes in the participation status of Attendees.
For instance, when Attendee "A" replies to Organizer
"O", and Attendee "B" receives a scheduling message
update from Organizer "O" with the new participation
status of Attendee "A", the CALDAV:schedule-tag
property of Attendee "B"s scheduling object resource
MUST NOT be changed.
The server MUST change the CALDAV:schedule-tag property
value when the scheduling object resource is changed
directly via an HTTP request (e.g., PUT, COPY or MOVE).
Clients can use the If-Schedule-Tag-Match request header to do
a PUT request that ensures that "inconsequential"
changes on the server do not result in a precondition
error. The value of the request header is set to the last
Schedule-Tag value received for the resource being modified.
If the value of the If-Schedule-Tag-Match header matches the
current value of the CALDAV:schedule-tag property the server
MUST take any "ATTENDEE" property changes for all Attendees
other than the owner of the scheduling object resource and
apply those to the new resource being stored.
Otherwise, the server MUST fail the request with a 412
Precondition Failed status code.
Clients can use the If-Schedule-Tag-Match request header to do
a DELETE request that ensures that "inconsequential"
changes on the server do not result in a precondition error. The
value of the request header is set to the last Schedule-Tag
value received for the resource being deleted.
If the value of the If-Schedule-Tag-Match header matches the
current value of the CALDAV:schedule-tag property the server
performs the normal DELETE request processing for the resource.
Otherwise, the server MUST fail the request with a 412
Precondition Failed status code.
Clients can use the If-Schedule-Tag-Match request header
to do COPY or MOVE requests that ensures that
"inconsequential" changes on the server do not result in a
precondition error. The value of the request header is set
to the last Schedule-Tag value received for the resource
being copied or moved.
If the value of the If-Schedule-Tag-Match header matches the
current value of the CALDAV:schedule-tag property the server
performs the normal COPY or MOVE request processing for
the resource.
Otherwise, the server MUST fail the request with a 412
Precondition Failed status code.
This section specifies additional requirements on the handling
of the "PARTSTAT" property parameter when the "SCHEDULE-AGENT"
property parameter on the corresponding "ATTENDEE" property is
set to the value "SERVER" or is not present.
Clients SHOULD, and servers MUST reset the "PARTSTAT" property
parameter value of all "ATTENDEE" properties, except the one
that corresponds to the Organizer, to "NEEDS-ACTION" when the
Organizer reschedules an event.
A reschedule of an event occurs when any "DTSTART", "DTEND",
"DURATION", "DUE", "RRULE", "RDATE", or "EXDATE" property changes
in a calendar component such that existing recurrence instances
are impacted by the changes, as shown in the table below.
PropertyDescriptionDTSTART DTEND DURATION DUEAny change to these properties MUST result in "PARTSTAT" being set to "NEEDS-ACTION"RRULEA change to or addition of this property that results in the addition of new recurring instances or a change in time for existing recurring instances MUST result in "PARTSTAT" being reset to "NEEDS-ACTION" on each affected component.RDATEA change to or addition of this property that results in the addition of new recurring instances or a change in time for existing recurring instances MUST result in "PARTSTAT" being reset to "NEEDS-ACTION" on each affected component.EXDATEA change to or removal of this property that results in the re-instatement of recurring instances MUST result in "PARTSTAT" being reset to "NEEDS-ACTION" on each affected component.
The server MAY allow the Organizer's client to change an
Attendee's "PARTSTAT" property parameter value to "NEEDS-ACTION"
at any other time (e.g., when the "LOCATION" property value
changes, an Organizer might wish to re-invite Attendees who
may be impacted by the change).
When scheduling with an Attendee there are two types of status information that can be returned during the transaction. The first status information is a "delivery" status that indicates whether the scheduling message from the Organizer to the Attendee was delivered or not, or what the current status of delivery is. The second status information is a "reply" status corresponding to the Attendee's own "REQUEST-STATUS" information from the scheduling message reply that is sent back to the Organizer.Similarly, when an Attendee sends a reply back to the Organizer, there will be "delivery" status information for the scheduling message sent to the Organizer. However, there is no "REQUEST-STATUS" sent back by the Organizer, so there is no equivalent of the "reply" status as per scheduling messages to Attendees.The "delivery" status information on an "ORGANIZER" or "ATTENDEE" iCalendar property is conveyed in the "SCHEDULE-STATUS" property parameter value (). The status code value for "delivery" status can be one of the following:Delivery Status CodeDescription1.0The scheduling message is pending. i.e. the server is still in the process of sending the message. The status code value can be expected to change once the server has completed its sending and delivery attempts.1.1The scheduling message has been successfully sent. However, the server does not have explicit information about whether the scheduling message was successfully delivered to the recipient. This state can occur with "store and forward" style scheduling protocols such as iMIP (iTIP using email).1.2The scheduling message has been successfully delivered.3.7The scheduling message was not delivered because the server did not recognize the calendar user address as a valid calendar user.3.8The scheduling message was not delivered due to insufficient privileges.5.1The scheduling message was not delivered because the server could not complete delivery of the message. This is likely due to a temporary failure, and the originator can try to send the message again at a later time.5.2The scheduling message was not delivered because the server was not able to find a suitable way to deliver the message. This is likely a permanent failure, and the originator should not try to send the message again, at least without verifying/correcting the calendar user address of the recipient.5.3The scheduling message was not delivered and was rejected because scheduling with that recipient is not allowed. This is likely a permanent failure, and the originator should not try to send the message again.The status code for "reply" status can be any of the valid iTIP "REQUEST-STATUS" values.The Organizer of a scheduled event may also be an Attendee of that event. In such cases the server MUST NOT send a scheduling message to the Attendee that matches the Organizer.
This specification defines additional iCalendar property
parameters to support the CalDAV scheduling extensions.
SCHEDULE-AGENT
To specify the agent expected to deliver scheduling
messages to the corresponding Organizer or Attendee.
This property parameter is defined by the following notation:
This property parameter MAY be specified on "ORGANIZER" or "ATTENDEE"
iCalendar properties. In the absence of this parameter, the
value "SERVER" MUST be used for the default behavior.
The value determines whether or not an automatic scheduling
transaction on a server will cause a scheduling message
to be sent to the corresponding Calendar User identified
by the "ORGANIZER" or "ATTENDEE" property value. When the value "SERVER"
is specified, or the parameter is absent, then it is the
server's responsibility to send a scheduling message as
part of an automatic scheduling transaction. When the value
"CLIENT" is specified, that indicates that the client
is handling scheduling messages with the Calendar User
itself. When "NONE" is specified, no scheduling messages
are being sent to the Calendar User.
Servers MUST NOT include this parameter in any scheduling
messages sent as the result of an automatic scheduling
transaction.
Clients SHOULD NOT include this parameter in any scheduling
messages that they themselves send.
Servers and clients MUST treat x-name and iana-token
values they don't recognize the same way as they would
the "NONE" value.
SCHEDULE-FORCE-SEND
To force a scheduling message to be sent to the Calendar
User specified by the property.
This property parameter is defined by the following notation:
This property parameter MAY be specified on "ATTENDEE"
and "ORGANIZER" properties on which the "SCHEDULE-AGENT"
property parameter is set to the value "SERVER" or is
not specified.
This property parameter is used to force a server to send
a scheduling message to a specific Calendar User in
situations where the server would not send a scheduling
message otherwise (e.g., when no change that warrants the
delivery of a new scheduling message was performed on
the scheduling object resource).
An Organizer MAY specify this parameter on an "ATTENDEE"
property with the value "REQUEST" to force a "REQUEST"
scheduling message to be sent to this Attendee.
An Attendee MAY specify this parameter on the "ORGANIZER"
with the value "REPLY" to force a "REPLY" scheduling
message to be sent to the Organizer.
Servers MUST NOT preserve this property parameter in
scheduling object resources, nor include it in any
scheduling messages sent as the result of an automatic
scheduling transaction.
Clients SHOULD NOT include this parameter in any scheduling
messages that they themselves send.
Servers MUST set the "SCHEDULE-STATUS" parameter of the
"ATTENDEE" or "ORGANIZER" to 2.3 (i.e., "Success, invalid
property parameter ignored", see Section 3.6 of
)
when the "SCHEDULE-FORCE-SEND" parameter is set to
a x-name or iana-token value they don't recognize.
SCHEDULE-STATUS
To specify the status codes returned from processing of the
most recent scheduling message sent to the corresponding
Attendee, or received from the corresponding Organizer.
This property parameter is defined by the following notation:
This property parameter MAY be specified on the "ATTENDEE"
and "ORGANIZER" properties.
Servers MUST add this property parameter to any "ATTENDEE"
properties corresponding to Calendar Users who were
sent a scheduling message via an automatic scheduling
transaction. Clients SHOULD NOT change or remove this
parameter if it was provided by the server. In the case
where the client is handling the scheduling, the client
MAY add, change or remove this parameter to indicate the
last scheduling message status it received.
Servers MUST add this parameter to any "ORGANIZER"
properties corresponding to Calendar Users who were sent
a scheduling message reply by an Attendee via an automatic
scheduling transaction. Clients SHOULD NOT change or remove
this parameter if it was provided by the server. In the
case where the client is handling the scheduling the client
MAY add, change or remove this parameter to indicate the
last scheduling message status it received.
Servers MUST NOT include this parameter in any scheduling messages sent as the result of an automatic scheduling transaction.Clients SHOULD NOT include this parameter in any scheduling messages that they themselves send.Suitable values for this property parameter are described in .
This specification defines additional HTTP request and response
headers for use with CalDAV.
When an Attendee removes a scheduling
object resource, and the Schedule-Reply header is not present,
or present and set to the value "T", the server MUST send an
appropriate reply scheduling message with the Attendee's
"PARTSTAT" iCalendar property parameter value set to "DECLINED"
as part of its normal automatic scheduling transaction
processing.
When the Schedule-Reply header is set to the value "F", the
server MUST NOT send a scheduling message as part of its
normal automatic scheduling transaction processing.
The Schedule-Reply request header is used by a client to
indicate to a server whether or not an automatic scheduling
transaction should occur when an Attendee deletes a scheduling
object resource. In particular it controls whether a reply
scheduling message is sent to the Organizer as a result of the
removal. There are situations in which unsolicited scheduling
messages need to be silently removed (or ignored) for security
or privacy reasons. This request header allows the scheduling
object resource to be removed if such a need arises.
All scheduling object resources MUST support the Schedule-Reply
request header.
The Schedule-Tag response header provides the current value of
the CALDAV:schedule-tag property value. The behavior of this
response header is described in .
All scheduling object resources MUST support the Schedule-Tag
header.
The If-Schedule-Tag-Match request header field is used with a
method to make it conditional. Clients can set this header to
the value returned in the Schedule-Tag response header, or the
CALDAV:schedule-tag property, of a scheduling object resource
previously retrieved from the server to avoid overwriting
"consequential" changes to the scheduling object resource.
All scheduling object resources MUST support the
If-Schedule-Tag-Match header.
The CalDAV scheduling extension defines the following new WebDAV
properties for use with CalDAV.
schedule-calendar-transpurn:ietf:params:xml:ns:caldavDetermines whether the calendar object resources in a calendar collection will affect the owner's freebusy.This property MAY be protected and SHOULD NOT be returned by a PROPFIND allprop request (as defined in Section 14.2 of ).This property value SHOULD be kept during a MOVE operation, but is normally re-initialized when a resource is created with a COPY. It should not be set in a COPY.This property SHOULD be defined on all calendar collections. If present, it contains one of two XML elements that indicate whether the calendar object resources in the calendar collection should contribute to the owner's freebusy or not. When the CALDAV:opaque element is used, all calendar object resources in the corresponding calendar collection MUST contribute to freebusy, assuming access privileges and other iCalendar properties allow it to. When the CALDAV:transparent XML element is used, the calendar object resources in the corresponding calendar collection MUST NOT contribute to freebusy.If this property is not present on a calendar collection, then the default value CALDAV:opaque MUST be assumed.
]]>
]]>schedule-default-calendar-URLurn:ietf:params:xml:ns:caldavSpecifies a default calendar for an Attendee where new scheduling object resources are created.This property MAY be protected in the case where a server does not support changing the default calendar, or does not support a default calendar.This property is only defined on a scheduling Inbox collection which cannot be moved or copied.This property MAY be defined on a scheduling Inbox collection. If present, it contains zero or one DAV:href XML elements. When a DAV:href element is present, its value indicates a URL to a calendar collection that is used as the default calendar. When no DAV:href element is present, it indicates that there is no default calendar. In the absence of this property there is no default calendar. When there is no default calendar the server is free to choose the calendar in which a new scheduling object resource is created. See .
]]>/home/cyrus/calendars/work/
]]>schedule-tagurn:ietf:params:xml:ns:caldavIndicates whether a scheduling object resource has had a "consequential" change made to it.opaque-tag (defined in Section 3.11 of )This property MUST be protected as only the server can update the value.This property is only defined on scheduling object resources. It MUST be preserved when a scheduling object resource is copied or moved and the resulting resource is also a scheduling object resource. If the source resource is not a scheduling object resource but the destination resource is, this property MUST be added to the destination resource.The CALDAV:schedule-tag property MUST be defined on all scheduling object resources. This property is described in .
]]>"12345-67890"
]]>CalDAV servers MUST support and adhere to the requirements of WebDAV ACL. Furthermore, CalDAV servers that advertise support for the "calendar-auto-schedule" feature MUST also support the scheduling privileges defined in this section.All the scheduling privileges MUST be non-abstract and MUST appear in the DAV:supported-privilege-set property of scheduling Outbox and Inbox collections on which they are defined.The tables specified in clarify which scheduling methods (e.g., "REQUEST", "REPLY", etc.) are controlled by each scheduling privilege defined in this section.This section defines new WebDAV ACL privileges that are for use on scheduling Inbox collections. These privileges determine whether delivery of scheduling messages from a calendar user is allowed by the calendar user who "owns" the scheduling Inbox collection. This allows calendar users to choose which other calendar users can schedule with them.Note that when a scheduling message is delivered to a calendar user, in addition to a scheduling object resource being created in the calendar user's scheduling Inbox collection, a new scheduling object resource might be created or an existing one updated in a calendar belonging to the calendar user. In that case, the ability to create or update the scheduling object resource in the calendar is controlled by the privileges assigned to the scheduling Inbox collection.The privileges defined in this section are ignored if applied to a resource other than a scheduling Inbox collection.CALDAV:schedule-deliver is an aggregate privilege that contains all the scheduling privileges that control the processing and delivery of incoming scheduling messages, that is, CALDAV:schedule-deliver-invite and CALDAV:schedule-deliver-reply, as well as freebusy requests targeted at the owner of the scheduling Inbox collection, that is, CALDAV:schedule-query-freebusy.]]>The CALDAV:schedule-deliver-invite privilege controls the processing and delivery of scheduling messages coming from an Organizer.]]>The CALDAV:schedule-deliver-reply privilege controls the processing and delivery of scheduling messages coming from an Attendee.]]>The CALDAV:schedule-query-freebusy privilege controls freebusy requests targeted at the owner of the scheduling Inbox collection.]]>This section defines new WebDAV ACL privileges that are defined for use on scheduling Outbox collections. These privileges determine which calendar users are allowed to send scheduling messages on behalf of the calendar user who "owns" the scheduling Outbox collection. This allows calendar users to choose other calendar users who can act on their behalf to send schedule messages to other calendar users (e.g. assistants working on behalf of their boss).The privileges defined in this section are ignored if applied to a resource other than a scheduling Outbox collection.CALDAV:schedule-send is an aggregate privilege that contains all the scheduling privileges that control the use of methods that will cause scheduling messages to be delivered to other users, that is, CALDAV-schedule-send-invite and CALDAV-schedule-send-reply, as well as freebusy requests to be targeted at other users, that is, CALDAV-schedule-send-freebusy.]]>The CALDAV:schedule-send-invite privilege controls the sending of scheduling messages by Organizers.Users granted the DAV:bind privilege on a calendar collection, or DAV:write privilege on scheduling object resources, will also need the CALDAV:schedule-send-invite privilege granted on the scheduling Outbox collection of the owner of the calendar collection or scheduling object resource in order to be allowed to create, modify or delete scheduling object resources in a way that will trigger the CalDAV server to deliver organizer scheduling messages to other calendar users.]]>The CALDAV:schedule-send-invite privilege controls the sending of scheduling messages by Attendees.Users granted the DAV:bind privilege on a calendar collection, or DAV:write privilege on scheduling object resources, will also need the CALDAV:schedule-send-reply privilege granted on the scheduling Outbox collection of the owner of the calendar collection or scheduling object resource in order to be allowed to create, modify or delete scheduling object resources in a way that will trigger the CalDAV server to deliver attendee scheduling messages to other calendar users.]]>The CALDAV:schedule-send-freebusy privilege controls the use of the POST method to submit scheduling messages that specify the scheduling method "REQUEST" with a "VFREEBUSY" calendar component.]]>Server implementations MUST aggregate the scheduling privileges as follows:
DAV:all MUST contain CALDAV:schedule-send and CALDAV:schedule-deliver;CALDAV:schedule-send MUST contain CALDAV:schedule-send-invite, CALDAV:schedule-send-reply, and CALDAV:schedule-send-freebusy;CALDAV:schedule-deliver MUST contain CALDAV:schedule-deliver-invite, CALDAV:schedule-deliver-reply, and CALDAV:schedule-query-freebusy.The following diagram illustrates how scheduling privileges are aggregated according to the above requirements.
This section defines new properties for WebDAV principal resources as defined in RFC3744. These properties are likely to be protected but the server MAY allow them to be written by appropriate users.schedule-inbox-URLurn:ietf:params:xml:ns:caldavIdentify the URL of the scheduling Inbox collection owned by the associated principal resource.This property MAY be protected.This property SHOULD NOT be returned by a PROPFIND allprop request (as defined in Section 14.2 of ).This property value SHOULD be preserved in COPY and MOVE operations.This property is needed for a client to determine where the scheduling Inbox collection of the current user is located so that processing of scheduling messages can occur.
]]>schedule-outbox-URLurn:ietf:params:xml:ns:caldavIdentify the URL of the scheduling Outbox collection owned by the associated principal resource.This property MAY be protected.This property SHOULD NOT be returned by a PROPFIND allprop request (as defined in Section 14.2 of ).This property value SHOULD be preserved in COPY and MOVE operations.This property is needed for a client to determine where the scheduling Outbox collection of the current user is located so that sending of scheduling messages can occur.
]]>calendar-user-address-seturn:ietf:params:xml:ns:caldavIdentify the calendar addresses of the associated principal resource.This property MAY be protected.This property SHOULD NOT be returned by a PROPFIND allprop request (as defined in Section 14.2 of ).This property value SHOULD be preserved in COPY and MOVE operations.Support for this property is REQUIRED. This property is needed to map calendar user addresses in iCalendar data to principal resources and their associated scheduling Inbox and Outbox collections. In the event that a user has no well defined identifier for their calendar user address, the URI of their principal resource can be used. This property SHOULD be searchable using the DAV:principal-property-search REPORT. The DAV:principal-search-property-set REPORT SHOULD identify this property as such.
]]>mailto:bernard@example.commailto:bernard.desruisseaux@example.com
]]>calendar-user-typeurn:ietf:params:xml:ns:caldavIdentifies the calendar user type of the associated principal resource.Same values allowed for the iCalendar "CUTYPE" property parameter defined in Section 3.2.3 of .This property MAY be protected.This property SHOULD NOT be returned by a PROPFIND allprop request (as defined in Section 14.2 of ).This property value SHOULD be preserved in COPY and MOVE operations.This property MAY be defined on principal resources to indicate the type of calendar user associated with this principal resource. Its value is the same as the iCalendar "CUTYPE" property parameter that can be used on "ATTENDEE" properties. This property SHOULD be searchable using the DAV:principal-property-search REPORT. The DAV:principal-search-property-set REPORT SHOULD identify this property as such.
]]>INDIVIDUAL<
/C:calendar-user-type>
]]>schedule-responseurn:ietf:params:xml:ns:caldavContains the set of responses for a POST method request.See .
]]>responseurn:ietf:params:xml:ns:caldavContains a single response for a POST method request.See .
]]>recipienturn:ietf:params:xml:ns:caldavThe calendar user address that the enclosing response for a POST method request is for.See .
]]>request-statusurn:ietf:params:xml:ns:caldavThe iTIP "REQUEST-STATUS" property value for this response.See .
]]>
The process of scheduling involves the sending and receiving of
scheduling messages. As a result, the security problems related
to messaging in general are relevant here. In particular the
authenticity of the scheduling messages needs to be verified.
Servers and clients MUST use an HTTP connection protected with
TLS as defined in for all scheduling
transactions.
When handling a scheduling transaction:
Servers MUST verify that the principal associated with
the DAV:owner of the calendar collection in which a
scheduling object resource is being manipulated contains a
CALDAV:schedule-outbox-URL property value.
Servers MUST verify that the currently authenticated user
has the CALDAV:schedule-send privilege, or a suitable sub-privilege aggregated under this privilege, on the scheduling Outbox collection of the DAV:owner of the calendar collection in which a scheduling
object resource is being manipulated.
Servers MUST only deliver scheduling messages to recipients
when the CALDAV:schedule-deliver privilege, or a suitable sub-privilege aggregated under this privilege, is granted on the recipient's scheduling Inbox collection for the principal associated with the DAV:owner of the calendar collection in which a scheduling
object resource is being manipulated.
To prevent impersonation of calendar users, the server MUST
verify that the "ORGANIZER" property in an organizer scheduling
object resource matches one of the calendar user addresses
of the DAV:owner of the calendar collection in which the
resource is stored.
To prevent spoofing of an existing scheduling object resource,
servers MUST verify that the "UID" iCalendar property value
in a new scheduling object resource does not match that
of an existing scheduling object resource with a different
"ORGANIZER" property value.
When handling a POST request on a scheduling Outbox collection:
Servers MUST verify that the principal associated with the
calendar user address specified in the "ORGANIZER" property
of the scheduling message data in the request contains a
CALDAV:schedule-outbox-URL property value that matches the
scheduling Outbox collection targeted by the request.
Servers MUST verify that the currently authenticated user
has the CALDAV:schedule-send privilege, or a sub-privilege aggregated under this privilege, on the scheduling Outbox collection targeted by the request.
Servers MUST only return valid freebusy information for recipients
when the CALDAV:schedule-deliver privilege, or a sub-privilege aggregated under this privilege, is granted on the recipient's scheduling Inbox collection for the principal associated with the DAV:owner of the scheduling Outbox collection targeted by the request.
As noted in , Attendees can use the Schedule-Reply request header with the value set to "F" to prevent notification to an Organizer that a scheduling object resource was deleted. This allows Attendees to remove unwanted scheduling messages without any response to the Organizer.
The message header fields below should be added to the Permanent
Message Header Field Registry (see ).
Header field name: Schedule-ReplyApplicable protocol: httpStatus: standardAuthor/Change controller: IETFSpecification document(s): this specification ()Related information: noneHeader field name: Schedule-TagApplicable protocol: httpStatus: standardAuthor/Change controller: IETFSpecification document(s): this specification ()Related information: noneHeader field name: If-Schedule-Tag-MatchApplicable protocol: httpStatus: standardAuthor/Change controller: IETFSpecification document(s): this specification ()Related information: none
The following iCalendar property parameters should be added to
the iCalendar Property Parameter Registry defined in Section
8.3.3 of .
ParameterStatusReferenceSCHEDULE-AGENTCurrentRFCXXXX, SCHEDULE-STATUSCurrentRFCXXXX, SCHEDULE-FORCE-SENDCurrentRFCXXXX,
The IANA should create and maintain the following additional
registries for iCalendar elements with pointers to
appropriate reference documents.
The following table should be used to initialize the
schedule agent values registry.
Schedule AgentStatusReferenceSERVERCurrentRFC XXXX, CLIENTCurrentRFC XXXX, NONECurrentRFC XXXX,
The following table should be used to initialize the
schedule send values registry.
Schedule Force SendStatusReferenceREQUESTCurrentRFC XXXX, REPLYCurrentRFC XXXX,
The authors would like to thank the following individuals
for contributing their ideas and support for writing this
specification:
Mike Douglass,
Lisa Dusseault,
Helge Hess,
Arnaud Quillaud,
Julian F. Reschke,
Wilfredo Sanchez Vega,
Simon Vaillancourt,
and Jim Whitehead.
The authors would also like to thank the Calendaring and Scheduling
Consortium for advice with this specification, and for organizing
interoperability testing events to help refine it.
&rfc2119;
&rfc2616;
&rfc2818;
&rfc3744;
&rfc3864;
&rfc4791;
&rfc4918;
&rfc5234;
&id2445bis;
&id2446bis;
&W3C.REC-xml-20081126;
&id2447bis;
&rfc3283;
The following tables specify which scheduling privileges
grant the right to a calendar user to deliver a scheduling
message to the scheduling Inbox collection of another
calendar user. The appropriate behavior depends on the
calendar component type as well as the scheduling "METHOD"
specified in the scheduling message.
The following tables specify which scheduling privileges
grant the right to a Calendar User to perform busy time
information requests and to submit scheduling messages
to other Calendar Users as the result of a scheduling
transaction. The appropriate behavior depends on the
calendar component type as well as the scheduling "METHOD"
specified in the scheduling message.
This section describes some example scheduling transactions that give
a general idea of how scheduling is carried out between CalDAV clients
and servers from the perspective of meeting Organizers and Attendees.
In the following examples the requests and responses are incomplete and are only for illustrative purposes. In particular, HTTP authentication headers and behaviors are not shown, even though they are required in normal operation.
In the following example, Cyrus invites Wilfredo, Bernard and Mike
to a single instance event by simply creating a new scheduling object
resource in one of his calendar collection by using the PUT method.
>> Request <<>> Response <<
Once the event creation has been completed, Cyrus's client will
retrieve the event back from the server to get the schedule
status of each Attendee. In this example, the server reports
that a scheduling message was delivered to Wilfredo, a scheduling
message is still pending for Bernard, and the server was unable
to deliver a scheduling message to Mike.
>> Request <<>> Response <<
In the following example, Wilfredo's client retrieves and deletes
the new scheduling message that appeared in his scheduling
Inbox collection after the server automatically processed it and
created a new scheduling object resource in his default calendar
collection.
>> Request <<>> Response <<>> Request <<>> Response <<
In the following example, Wilfredo's accepts Cyrus's invitation
and sets a reminder on the event.
>> Request <<>> Response <<
Once the event modification has been completed, Wilfredo's client
will retrieve the event back from the server to get the schedule
status of the Organizer.
>> Request <<>> Response <<
On reception of Wilfredo's reply, Cyrus's server will
automatically update Cyrus's scheduling object resource, make
Wilfredo's scheduling message available in Cyrus's scheduling Inbox
collection, and deliver an updated scheduling message to Bernard to
share Wilfredo's updated participation status. In this example,
Cyrus's client retrieves and deletes this scheduling message in his
scheduling Inbox collection.
>> Request <<>> Response <<>> Request <<>> Response <<
Cyrus's client then retrieves the event back from the server
with Wilfredo's updated participation status.
>> Request <<>> Response <<
In this example, Cyrus requests the busy time information
of Wilfredo and Bernard.
>> Request <<>> Response <<mailto:wilfredo@example.com2.0;SuccessBEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Example Corp.//CalDAV Server//EN
METHOD:REPLY
BEGIN:VFREEBUSY
UID:4FD3AD926350
DTSTAMP:20090602T200733Z
DTSTART:20090602T000000Z
DTEND:20090604T000000Z
ORGANIZER;CN="Cyrus Daboo":mailto:cyrus@example.com
ATTENDEE;CN="Wilfredo Sanchez Vega":mailto:wilfredo@example.com
FREEBUSY;FBTYPE=BUSY:20090602T110000Z/20090602T120000Z
FREEBUSY;FBTYPE=BUSY:20090603T170000Z/20090603T180000Z
END:VFREEBUSY
END:VCALENDAR
mailto:bernard@example.net2.0;SuccessBEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Example Corp.//CalDAV Server//EN
METHOD:REPLY
BEGIN:VFREEBUSY
UID:4FD3AD926350
DTSTAMP:20090602T200733Z
DTSTART:20090602T000000Z
DTEND:20090604T000000Z
ORGANIZER;CN="Cyrus Daboo":mailto:cyrus@example.com
ATTENDEE;CN="Bernard Desruisseaux":mailto:bernard@example.net
FREEBUSY;FBTYPE=BUSY:20090602T150000Z/20090602T160000Z
FREEBUSY;FBTYPE=BUSY:20090603T090000Z/20090603T100000Z
FREEBUSY;FBTYPE=BUSY:20090603T180000Z/20090603T190000Z
END:VFREEBUSY
END:VCALENDAR
mailto:mike@example.org3.7;Invalid calendar user
]]>
In the following example, Cyrus attempts to create,
on behalf of Wilfredo, an event with Bernard specified
as an Attendee. The request fails since Wilfredo didn't
grant Cyrus the right to invite other Calendar Users
on his behalf.
>> Request <<>> Response <</home/wilfredo/calendars/outbox/
]]>
In the following example, Bernard declines the second recurrence
instance of a daily recurring event he's been invited to by Cyrus.
>> Request <<>> Response <<
Bernard's participation status update will cause his
server to deliver a scheduling message to Cyrus.
Cyrus's client will find the following reply message
from Bernard in Cyrus's scheduling Inbox collection:
>> Request <<>> Response <<
In the following example, Bernard removes from his calendar the
third recurrence instance of a daily recurring event he's been
invited to by Cyrus. This is accomplished by the addition of an "EXDATE" property to the scheduling object resource stored by Bernard.
>> Request <<
Bernard's deletion of a recurrence instance will cause his
server to deliver a scheduling message to Cyrus.
Cyrus's client will find the following reply message
from Bernard in Cyrus's scheduling Inbox collection:
>> Request <<>> Response <<
Added "Updates 4791".
XML conventions changed to match that in CardDAV spec.
Reworded child response behavior for Outbox.
Reworded "octet size".
If-Schedule-Match descriptions changed to remove implication that it is purely a conditional operation.
Schedule-Reply header descriptions generalized to resource removal rather than just HTTP DELETE.
Fixed various examples.
Restructured document.
Clarified that CALDAV:schedule-calendar-transp only
applies to calendar collection.
Removed CALDAV:schedule-state property on scheduling
messages in the scheduling Inbox collection.
Added conditional requests on scheduling object resources.
Added section on handling of PARTSTAT.
Added SCHEDULE-FORCE-SEND iCalendar property parameter.
Added clarification on child resources in scheduling Outbox
collections.
Clarified Attendee changes that server MUST allow, and
removed restrictions on changes that Attendee MUST NOT do.
Added Example Scheduling Transactions appendix.
Scheduling privileges are no longer required to be
non-abstract.
Removed handling of REFRESH requests.
Removed handling of VJOURNAL components.
Completed IANA Considerations section.
Added references to RFC3283 and RFC5234.
Updated references to iCalendar, iTIP and iMIP.
Removed distinction between scheduling calendar collections
and basic calendar collections - now just have calendar
collections.
Clients now "MAY" reload data rather than "SHOULD" reload
data.
Fixed <C:recipient> in examples.
Removed CALDAV:attachments-allowed precondition on POST to
Outbox as that is no longer relevant.
Added CALDAV:default-calendar-delete-allowed precondition
for DELETE.
Relaxed MUST->MAY for Organizer setting PARTSTAT value.
Tweaked restrictions on Create/Modify to emphasize that 4791
restrictions also apply.
Added comment that 'opaque' is the default when the
CALDAV:schedule-calendar-transp property is not present.
Description of Schedule-Reply header changed to reflect that
it is only relevant for Attendees.
Minor typos fixed.
This draft has changed substantially since the -04 version. The
primary reason for this change was implementation experience from
a number of vendors who implemented products based on the earlier
drafts. Experience showed that the client/server interaction was
not reliable in keeping scheduling messages synchronized between
organizer and attendees. In addition the latency in updates due
to clients being offline proved unacceptable to users. These
issues led to the redesign of this specification to support a
server-based processing model that eliminates all the problems
seen previously. Whilst this adds significant complexity to the
server in that it needs to be a full blown iTIP processing agent,
it does remove a lot of the same complexity from clients, opening
up the possibility of supporting complex scheduling behaviors
even with "thin" clients.
In the judgement of the authors, we consider this new specification
to be a substantial improvement over the old one and believe
it represents a stronger protocol that will lead to better
interoperability.